1. Field of the Invention
This invention relates to liquid fabric softener compositions. More particularly it relates to clear, liquid fabric softener compositions that also impart static control with lower staining properties and enhanced shelf life.
2. Description of the Related Art
Fabric softener compositions have been employed in the past to render washed laundry articles softer to the touch and hence enhance wearer comfort. These compositions encompass solutions, emulsions and particulate or powder compositions, such as, paper strips or sheets impregnated with fabric softener compositions. Most commercial products have included quaternary ammonium salts, such as, dimethyl ditallowyl ammonium chloride with emulsions of such softeners being added to the rinse water in the washing machine to effect softening of the laundry. As a variation on the theme, emulsions or powder products containing fabric softeners have been added to the wash water along with a detergent or the detergent composition can have incorporated into it a fabric softening component to make a so-called "softergent". In still another variation, articles containing a fabric softening component, such as a quaternary ammonium salt, can be added to the automatic laundry drier, where during tumbling of the laundry in a heated atmosphere, the fabric softener is applied to the laundry by repeated contact, thereby softening the laundered fabrics.
Other components in fabric softening compositions have been suggested including such as, neoalkanamides, glyceryl esters, glycol esters, silicones, cationic-anionic complexes, bentonite clays, and the like.
U.S. Pat. No. 3,928,212 describes softening agents which are polyhydric alcohol esters.
U.S. Pat. No. 4,126,562 mentions aerythritol and pentaerythritol which may be reacted with higher alcohols to produce fabric softeners, and combinations of quaternary ammonium salts with nonionic alcohol esters of higher fatty acids.
U.S. Pat. No. 4,142,978 discloses sorbitan esters combined with phase modifying components, such as, alkyl sulfates on a dryer sheet for softening laundry while it is being tumble dried in an automatic laundry dryer.
U.S. Pat. No. 4,162,984 relates to a textile treatment emulsion of a water insoluble cationic fabric softener, that is preferably a quaternary ammonium salt or an alkylimidazolium salt with a water insoluble nonionic fabric softener that is preferably a fatty acid ester of a mono- or polyhydric alcohol and an aromatic mono- or dicarboxylic acid.
U.S. Pat. No. 4,214,038 discloses polyglycerol esters as softening agents.
U.S. Pat. No. 5,126,060 discloses and claims a fabric softening, aqueous emulsion which comprises a higher aliphatic acid ester of pentaerythritol and emulsifying agent free of quaternary ammonium fabric softeners for a clear, liquid, water-soluble fabric softening agent.
U.S. Pat. No. 4,569,800 discloses and claims the use of hydrogenated tallowyl 2-ethylhexyl dimethylammonium chloride as a fabric softening compound.
However these and other art compositions do not satisfy a commercial market demand for a clear, water-soluble, cationic fabric softener composition that also provides good static control, minimal staining and enhanced shelf life.
It is an object of this invention to provide clear, completely water-soluble cationic fabric softener compositions that also provide good static control.
It is another object to provide clear cationic fabric softener compositions that are soluble in solvents other than water.
It is still another object to provide clear cationic fabric softener compositions that exhibit enhanced color stability, shelf life and stain resistance.
Other objects will become apparent to those skilled in the art upon a further reading of the specification.
3. Summary of the Invention
The objects enumerated above have been satisfied by a clear, water-soluble composition comprising:
(A) about 3 to about 90% by weight of a blend of:
(1) a quaternary salt having the structure: ##STR1## wherein R is the radical residuum of a mixture of saturated and unsaturated fatty acids having about 12 to about 18 carbon atoms, R' is an alkyl radical having about to about 12 carbon atoms, and X is a halide radical or --SO.sub.3 CH.sub.3 ; with PA1 (2) an amido imidazolinium compound of the structure: ##STR2## wherein R.sub.1 and R.sub.2 are each mixtures of the radical residua of saturated and unsaturated fatty acids having about 12 to about 18 carbon atoms; and
(B) the remainder, water.
It is preferred to also include a solvent in the compositions of this invention. Suitable solvents include lower aliphatic alcohols, e.g., ethanol, isopropanol and the like or more preferably lower aliphatic glycols, e.g., ethylene glycol, propylene glycol, an hexylene glycol, either a straight chain one, viz. 1,6-hexanediol or 2,3-hexanediol or a branched chain one, viz. 2-methyl-2,4-pentanediol, 3-methyl-2,4,-pentanediol, 2,3-dimethyl-2,3-butanediol and the like. The presence of these monohydric or dihydric compounds has been found to improve the mutual solubility of the cationic components and hence the clarity of the total composition. The solvent level of the total composition may range from about 10 to about 40 weight percent. Optimum product clarity was achieved at a solvent level ratio of about 1:1 with the cationic fabric softening compounds.
These softener compositions may also contain various additives, as for example, perfumes or fragrances, colorants, bacteriostatic agents, and the like.
In a preferred embodiment of this invention, these softeners compositions also contain a stabilizing amount of a color stabilizer to enhance the shelf life of the product. Suitable color stabilizers include alkali metal bisulfites, such as, lithium, sodium or potassium bisulfites, and the like at a level of about 0.01 to about 0.5 weight percent of the total composition. Natural reducing agents can also be used, vizo, citric acid or ascorbic acid and the like. However, interaction with some fragrances may occur. If used, a preferred level is about 0.2 to about 2.0 percent of the total composition. As a caveat, it has been found that certain aromatic acid salts, such as, sodium benzoate are unacceptable due to the formation of a precipitate during aging thus shortening the shelf life of the softener compositions.
4. Description of the Invention
The quaternary salts of component (A) above can be prepared by condensing an aliphatic alcohol with a fatty acid amine, hydrogenating the resultant imine to a secondary amine, followed by methylation. The salt is determined by the nature of the methylating agent. Thus a methyl halide produces a quaternary halide and dimethyl sulfate produces a quaternary sulfate or methyl sulfate.
An economical source of fatty acids is available through the hydrolysis of naturally occurring fats. These include beef tallow, butter, coconut oil, corn oil, cottonseed oil, lard, corn oil, palm oil, palm kernel oil, soybean oil, and the like. Some quaternary salts are commercially, as for example, hydrogenated tallow octyldimonium methosulfate from Akzo Nobel Co.
The amido imidazolinium compounds may be prepared from the amido/amine resulting from the reaction of fatty acids or triglycerides with diethylene triamine followed by heating at a temperature of 350.degree. to 450.degree. F. (177.degree. to 232.degree. C.) to effect ring closure and then quaternizing with dimethyl sulfate as shown below: ##STR3## where R is as defined above.
This preparation is delineated in the papers by R. R. Egan, J. Am. Oil Chemists' Soc., January 1978 (Vol. 55) and J. A. Ackerman, JAOCS, Vol. 60, No. 6 (1983) incorporated herein by reference.
In order to achieve optimum clarity and static control together with product stability, these fabric softener compositions should have a pH of about 4 to about 8 with a preferred range of about 5 to about 6.
The invention is further described in the examples which follow. All parts and percentages are by weight unless otherwise specified.